12166 resync smatch to 0.6.1-rc1-il-3

*** 1093,1102 ****
--- 1093,1111 ----
  {
          struct stree *stree;
          struct stree *implied_stree;
  
          stree = pop_stree(&switch_stack);
+         if (!stree) {
+                 /*
+                  * If the cur_stree was NULL before the start of the switch
+                  * statement then we don't want to unnullify it.
+                  *
+                  */
+                 push_stree(&switch_stack, stree);
+                 return;
+         }
          implied_stree = __implied_case_stree(switch_expr, case_rl, &remaining_cases, &stree);
          merge_stree(&cur_stree, implied_stree);
          free_stree(&implied_stree);
          push_stree(&switch_stack, stree);
  }